Astro-Physics (A-P) is almost legendary in the amateur astronomy community, mainly because of the outstanding apochromatic refractors this Illinois company produces. Surprisingly, A-P is also revered by CAT users due to its line of heavy-duty go-to GEMs, mounts with sterling reputations for quality and capability. A-P produces a full line of mounts, led by the newly introduced 3600GTO, the El Capitan, a monster of a GEM that is able to support scopes weighing up to 250 pounds. Not many SCT users outside those lucky folks who own vintage Celestron C22s or new Meade 20-inchers will need a mount in that weight (and price) class, but AstroPhysics sells three other mounts (the Mach1 GTO, the 900GTO, and the 1200GTO) well suited to the needs of 8- to 16-inch SCT owners.
The Mach1GTO ($5,950) is A-P's "light mount," but that is in relative terms. This GEM is more than able to accommodate CATs in the 8- to 12-inch aperture range, at least (Astro-Physics, unlike other GEM makers, tends to underrate the payload capacities of its mounts). One thing that is surprising about the Mach1 is that it is able to handle telescopes as heavy as it is without becoming heavy itself. The mount head is a positively puny sounding 28 pounds. When it comes to electronics, the Mach1, like other A-Ps, tends to take the tried-and-true rather than innovative route. The GEM is driven by heavy-duty servo motors under the direction of a computer HC. The hand control is nothing fancy, containing 17,000 objects and an array of features similar to those of other go-to HCs. Since the A-P go-to system "speaks" Meade LX200, it can be controlled by any PC program suitable for a Meade scope. The draw is not tons of features; it is build quality and precision, both for the computer and the mount itself. Out of the box, without PEC training, the Mach1 boasts a periodic error of 7 arc seconds, which is better than the best periodic error of many PEC-trained mounts.
Got a C14? Do not want to just look at pretty stuff with it, but instead want to undertake a serious program of imaging? Step up to the 900GTO ($8,250). Despite a still "reasonable" GEM head weight of 54 pounds, this thing packs a punch—a payload capacity of 70 pounds. Does 54 pounds of mount head sound like a lot to lift onto a tripod? Never fear—the GEM head breaks down into easily manageable pieces. The heaviest part is only 25 pounds. The 900 will not just accommodate the C14 or the heavier Meade 14-inch OTA; it will allow imagers to add considerable ancillary gear such as sizable guide scopes. Other than its much more noticeable beefiness, the 900 is much like the Mach1: high-quality servos, excellent build quality, and impressive accuracy. Its large brass worm gears deliver the same 7-arc-second tracking accuracy as the Mach1, good enough to allow many astrophotographers to take pictures without guiding.
Then, there is the 1200GTO ($9,400). The main descriptor for this mount is not "portable," but "transportable." Folks can be seen setting these up at star parties, but there is no denying the 81 pound equatorial head is big and heavy. This is not a mount to be carried out into the backyard on the spur of the moment, although one person could do that since the heaviest component is "only" 50 pounds. Naturally, this big gun is most at home in a permanent installation, and in that role it is hard to want for more than the 1200. It can handle an OTA of up to 140 pounds according to A-P, but users have pushed the 1200 past even that with great results.
So, who is the 1200GTO for? Perhaps it is for someone with a large OTA, a 16-inch, for example, who wants precision and build quality without leaving behind the comfortable punch-objects-into-an-HC-and-go-to-them paradigm. Accuracy? The 1200 is even better than her little sisters, with a stated error of an amazing 5 arc seconds or less.
Why should you not buy an A-P GEM? For many CAT fanciers, the stumbling block is money. The prices mentioned, by the way, are just for the GEM head. Prospective purchasers will need to invest more for a full-up system with a pier, a mounting plate for the OTA, and counterweights, and those three things will elevate the price tag another $1,000 on average. And yet, and yet, ... plenty of folks think nothing of paying this much or more for a couple of jet skis that sit in the garage most of the year. For the person with the need and the means, it is hard not to say "go A-P." One thing that dissuaded some prospective A-P GEM purchasers in the past was the long wait times for mount deliveries, which approached the lengthy waiting periods required of buyer's of the company's refractors. In recent years, A-P has stepped up GEM production, and the GTOs are considerably easier to get than they once were. They are still not off-the-shelf items, however.
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